Planned build - feedback requested

I'm a torchlight newb with a penchant for **** -- those two things don't always go well together, but I'll hopefully kill less characters as I learn more. It would help to have a workable build for **** "hard" difficulty, as well, and feedback about the broad outlines of the "mage" build I have down below would be helpful and appreciated:

Utility:
Advanced Spellcasting (10) - not sure when this becomes important, I'll probably add points when mana seems to run low
Adventurer (5 - 10) - a few points early, then build up late
Treasure Hunter (1, later 10) - a point or two early, then build up late

Skills I have questions about:
Infuse - does it help skills based on % weapon damage, or only direct weapon usage?
Pet Mastery - How well does my pet hold up without it?

Comments

from my experience, heal is not that good, potions are better than the heal skill, but heal all is better than potions.
this is how it works:
Heal, recovers a set amount of HP of caster, not affected by Adventurer Skill and Potion Effectiveness
Potions, recovers a set amount of HP of caster but effect can be increased by Adventurer Skill and Potion Effectiveness item effect
Heal All, the same as potions as it will be affected by Potion Effectiveness but will heal your party including summon and pet

Silence and Web are just a waste of you spell slots, they are often given to pets

Ember Phase should only be left at level 1, this skill should not be chosen as a DPS skill, you'll only have to use it for the teleport effect and knockback but not the damage itself

Terror 1 is essential

Defensive Magic isn't important, Heal All in itself synergized with the Adventurer Skill is enough to cover your HP from 1 to max, Elemental Protection can easily be replaced with element protection gems, the only important element to consider anyway is lighting, with proper kiting, the only spell that can reach you is the zealot's lighting, this is a very deadly skill and will 1HKO you if you have low lightning resist, other defensive skills are not important for alchemists

ember bolt is useless later on in the game, don't level it
ember strike at level 1 is enough, the damage gain is not that high, but the mana consumption increases significantly, better use the sp's on other skills

Utility:
Advanced Spellcasting (10) - not sure when this becomes important, I'll probably add points when mana seems to run low
Adventurer (5 - 10) - a few points early, then build up late
Treasure Hunter (1, later 10) - a point or two early, then build up late

since you'll be using ember strike, advance spellcasting is needed, strike will drain your mana very fast
adventurer skill should be prioritized and should be maxed out as soon as possible, check link below for explanation
treasure hunter isn't actually that important in my opinion, gold is easy to come by

i believe that "offense is the best defense", using shields may increase you defense and blocking but it will drastically decrease your total DPS, i suggest that you use dual weapons since weapons have better item effects
going in melee range is practically suicide for alchemists, better plan a build that keeps distance and prioritizes long range skills

Thank you for some detailed and (very!) helpful feedback. I'll make quite a few adjustments, based on your feedback.

- The adventurer skill will get a much higher place in the priority list and I'll not bother with the heal spell or defensive spell mastery.
- advanced spellcasting will be built up much quicker.
- I'll keep ember strike at one point.
- ember phase will stay at one point.
- I've seen my pet waste mana on buffs while out of battle already; your point seems well taken on that issue as well, and so I'll skip buff spells for my pet
- Dual wielding is inherently cooler and I may buff that skill, then, instead of relying on a shield and blocking

I'll keep putting points into ember bolt, though. Otherwise I have no damaging spell for mobs right next to me. Plus, I get three more bolts by building it up, for better knockback against crowds in close proximity. I also see ember bolt as a "pre-fire" spell for alpha at range; while it's traveling toward mobs I can land an ember strike. If they start to charge my alchemist, then ember bolt is already on its way to knock them back, when they try to surge forward. I believe you when you say it's not optimal, but I'm hopeful about finding ways to make it still ultimately useful.

I'll keep putting points into ember bolt, though. Otherwise I have no damaging spell for mobs right next to me. Plus, I get three more bolts by building it up, for better knockback against crowds in close proximity.

the reason why i think you should skip bolts is because you already have 2 spammable skills for knocking back mobs, phase and terror, spamming terror practically makes you invulnerable unless the monsters are right next to you, if this happens you can just phase out, terror is a very badass spell it has knockback and a flee chance so you better try it our first for knockback utility, also, the damage gain for bolts is not that high, but it is still up to you